Botulinum toxin is a potential bioweapon that can be used in acts of bioterrorism or biological warfare. Although the toxin is extraordinarily potent, there is little likelihood that there will be universal vaccination of the public. This can be attributed to two facts: a.) the perceived risk associated with use of the toxin as a bioweapon does not, at the present time, warrant universal vaccination, and b.) the toxin is a therapeutic agent for the treatment of neurologic, neuro-opthalmologic and related disorders, and universal vaccination would deprive patients who may need these therapeutic benefits. However, there are certain populations in whom vaccination would be warranted. These range from health care workers who may be first responders to members of the military services assigned to areas where there could be bioweapons. The goal of the proposed research is to develop a modern vaccine that will meet the needs of these vulnerable populations. This will be accomplished by pursuing three goals, each of which represents a significant improvement over current vaccine technology. First, site-directed mutagenesis will be used to create novel vaccine candidates that do not bind to cholinergic nerve endings, and therefore cannot evoke adverse neurologic side effects. Second, fusion genes will be constructed that will permit expression of chimeric polypeptides that are multivalent, non-neurotropic vaccines against two of the botulinum toxin serotypes (A, B) that pose the greatest threat to human health. Third, non-neurotropic multivalent constructs will be tested as mucosal vaccines that will evoke secretory antibodies that will block toxin absorption into the body. In the aggregate, these three advancements will lead to botulinum toxin vaccine that is superior to any other product that has been described. PUBLIC HEALTH RELEVANCE: Botulinum toxin is a microbial agent that causes the disease botulism. Naturally occurring botulism is not common, and thus there is no need for universal vaccination. However, botulism that is the product of bioterrorism or biological warfare could pose a high risk to certain populations, ranging from health care workers to members of the military, and these select populations may need access to a vaccine. Therefore, the goal of the proposed work is to develop a mucosal vaccine that will protect vulnerable populations against the use of botulinum toxin as a bioweapon.